Bis(trifluoromethylthio) fluorobutanes

ABSTRACT

BIS(TRIFLUOROMETHYLTHIO) FLUOROBUTANES USEFUL AS THERMALLY STABLE DIELECTRIC COOLANTS OR INSECTICIDAL FUMIGANTS, AND PROCESS FOR PREPARING THEM BY SUBJECTING A VAPOROUS MIXTURE OF HIS(TRIFLUOROMETHYL)DISULFIDE AND CERTAIN FLUOROETHYLENES TO ULTRAVIOLET LIGHT IN THE WAVE LENGHT RANGE BETWEEN ABOUT 2000A.AND ABOUT 3600A.AT TEMPERATURES OF AT LEAST ABOUT 35*C.   D R A W I N G

Feb. 29, 1972 R. E. A. DEAR ErAL 3,646,221

BIS IFLUOROMETHYLTHIO) .FLUORQBUTANES Filed Sept. 12, 1969 2 4 I3 l IllT I4 3 v l f 1 i WI 'J f I F E i ll I I I rwvrarrmres ROBERT E.A. DEAREVERETT E. GILBERT ATTORNEY 3,646,221 BIS(TRIFLUOROMETHYLTHIO)FLUOROBUTANES Robert E. A. Dear and Everett E. Gilbert, Morris Township,Morris County, N.J., assiguors to Allied Chemical Corporation, New York,N.Y.

Filed Sept. 12, 1969, Ser. No. 857,428 Int. Cl. C07c 149/16 US. Cl.260-609 A 4 Claims ABSTRACT OF THE DISCLOSURE Bis(trifiuoromethylthio)fluorobutanes useful as thermally stable dielectric coolants orinsecticidal fumigants, and process for preparing them by subjecting avaporous mixture of his (trifluoromethyl)disulfide and certainfiuoroethylenes to ultraviolet light in the wave length range betweenabout 2000 A. and about 3600 A. at temperatures of at least about 35 C.

This invention relates to a new method for preparingbis(trifluoromethylthio) fluorobutanes and to new bis(trifluoromethylthio) fiuorobutanes thus produced.

In the past, saturated organic compounds containing one or moretetrafluoroethylene groups per molecule have been prepared by heating anorganic sulfur compound such as dimethyl disulfide with a completelyhalogenated fiuoroethylene such as tetrafiuoroethylene, at a temperatureranging from 75 C. to 350 C. in the presence of a peroxy catalyst. Thisprocedure was effective in producing compounds of the character of nbeing an integer from 1 to 25, wherein the organic sulfide used was ahydrocarbon sulfide, i.e. a non-halogenated sulfide.

However, when a completely halogenated disulfide such as bis(trifiuoromethyDdisulfide is substituted for dimethyl disulfide in theprior art method referred to above the corresponding bis(trifluoromethylthio) fiuoroalkane is not obtained, and only highmolecular weight polymers result, which contain no sulfur.

It is an object of the present invention to provide a process forpreparing bis(trifiuoromethylthio) fiuorobu tanes in substantial yieldsand high purity by a simple procedure adapted for commercial operation.

This and other objects are accomplished according to our inventionwherein a mixture of bis(trifiuoromethyl) disulfide and fiuoroethylenecontaining at least two fluorine atoms are subjected to ultravioletlight in the wave length range between about 2000 A. and about 3600 A.at a temperature of at least about 35 C., preferably between about 35 C.and about 100 C.

The reaction is preferably carried out in the vapor phase since thefiuoroethylene is a gas at normal atmospheric conditions, and the his(trifluoromethyl)disulfide is a low boiling (B.P. 34 C.), easily'vaporizable liquid.

The ultraviolet light used in the irradiation should be of wave lengthswithin the range specified, and preferably should emit a substantialamount of radiation in the region of about 2330 A. since this is thewave length at which bis(trifluoromethyl)-disulfide has maximumultraviolet absorption. The reaction is usually substantially completein a period of no more than about 5 hours, more usually in a period ofabout 1 hour to about 3 hours.

The reaction according to our invention proceeds as follows:

United States Patent 0 'ice.

wherein X and Y are hydrogen, fluorine or chlorine with the proviso thatonly one of X and Y can be chlorine and that when X is hydrogen, Y isalso hydrogen.

Specific fluoroethylenes usable as starting materials in our reactioninclude the following:

('I) Tetrafluoroethylene, CF =CF (II) Trifluoromonochloroethylene, CFCFCI (III) Difl-uoroethylene, CFFCH The process of our invention can becarried out either batchwise or continuously, and appropriate apparatusis readily available for carrying out our photochemical reaction ineither manner using immersion type ultraviolet sources.

In the drawing, the single figure depicts, in half section, an apparatussuitable for carrying out our process batch-wise in the vapor phase.

'In carrying out the process, the bis(trifiuoromethyl) disulfide ispreferably vaporized and is mixed with the gaseous fiuoroethylene andthe mixture irradiated at temperatures of at least about 35 C. withultra-violet light in the wave length range between about 2000 R. andabout 3600* A.

The ultraviolet light can be supplied in any desired manner. Forexample, if the reaction vessel is of ultraviolet light-transparentmaterial such as quartz, the UV source can be positioned outside thevessel. Preferably the ultraviolet light source is positioned inside thereaction vessel, for example encased in a water cooled quartz well orother conventional device for supplying ultraviolet irradiation.

dn the preferred vapor phase reaction of our process, a mixture offiuoroethylene gas and 'vaporized bis(trifluoromethyl)disulfide isirradiated with ultraviolet light of the indicated wave length, eitherin a continuous reactor through which the mixture is passed, or in abatch reactor in which the mixture is maintained in an irradiated zoneat a temperature above the 34 C. boiling point of thebis(trifiuoromethyl)disulfide, i.e. sufficiently high to maintain thereactants in the vapor phase.

In examplary vapor phase reaction procedures, suitable for batchwisereactions, we may utilize the apparatus shown in the drawing.

Referring to the drawing, in the single figure, numeral 1 represents avapor phase batch reactor. Numeral 2 represents a water-cooled quartzwell within the reactor equipped with liquid coolant inlet at 3 and aliquid outlet at 4. Positioned within the liquid cooled well 2, isultraviolet lamp 5 with electrical terminals 6 and 7, connectedrespectively to ends 8 and 9 thereof and to a source of electric current(not shown). Reactor 1 is equipped at the bottom with neck 15 connectingreaction zone 10 with gas inlet 16 located at about the mid-point ofsaid neck. Removably attached to the end of reactor neck 15 isvaporizing vessel 17 shown partially filled with liquid reactant 18 andequipped with heating mantle 19. A vapor exit 11 is provided near thetop of the reactor, said exit being connected to a cold trap 12containing Dry Ice 13 and equipped with vapor exit 14. Trap 12 isconnected by line 21 having surge elbow 20 to vaporizing vessel 17 toprovide return of condensed reactant and reaction product to thevaporization vessel.

The compounds produced according to our invention are novel and areuseful for a number of purposes. The perfluoro compounds, as well as thepolyfluorocompounds having no more than 2 chlorine atoms, are thermallyquite stable and hence are useful as inert liquid reaction media, and asdielectric coolants. Compositions of the invention in this category aredesignated by the following general formula:

wherein Q and Z represent the sameor different members selected fromfluorine and chlorine.

The single compound of our invention which contains hydrogen, namely FCSCF CH CH CF SCF is less thermally stable than the perhalogenatedcompounds recited above. It has been found to be a valuable insecticidalfumigant useful in combatting many common insects includ ing confusedflour beetle (T ribolium confusum), black carpet beetle (Attagenuspiceus) yellow meal worm (T enebrio molitar), as well as nematodes(Panagrellus redivivus).

The following specific examples further illustrate our invention.

EXAMPLE 1 Bis(trifluoromethyhdisulfide (24 grams, 0.124 mol) was placedin a round bottom flask having a neck connected to the bottom of a vaporphase reactor similar to that shown in the drawing. The reactor wasprovided with a liquid cooled well having positioned therein a quartzmercury vapor lamp (Hanovia 450W) delivering ultraviolet light of wavelengths in the range between 2000 A. and 3600 A., and having a gas inletnear the bottom of the reactor and a vapor outlet near the top thereofleading to a cold trap containing Dry Ice. The bis(trifluoromethyl)disulflde (B.P. 34 C.) was heated and refluxed from the flask into thereaction zone of the reactor while tetrafluoroethylene gas wasconcurrently passed into the reaction zone through the gas inlet at arate of approximately 3 liters per hour (approximately 13.5 grams perhour). The mixture was irradiated with ultraviolet light from the lamp,whereupon reaction took place, the resulting liquid product beingcondensed in the cold trap and returned to the refluxing liquid. Thetemperature of the refluxing liquid was noted at intervals, and over aperiod of two hours it rose from 36 C. to 71 C. The vapor temperature inthe reactor was therefore also within this range. When no furthertemperature rise occurred, at this point the irradiation wasdiscontinued and liquid in the flask was removed and distilled through aspinning band column yielding 16 grams (a 39.3% yield) of a mainfraction of 1,4-bis(trifluoromethylthio) perfiuorobutane, together with4 grams unreacted CF SSCF and 5 grams of CF SCF CF SCF B.P. 808l C.

The identity of the above compounds was confirmed by F N.M.R., by massspectroscopy and by elemental analysis, the latter showing:

Calcd. for CF SCF CF SCF (percent): C, 15.90; S, 21.22. Found (percent):C, 15.72; S, 20.90.

Calcd. for CF SCF CF CF CF SCF (percent): C, 17.92; S, 15.94. Found(percent): C, 18.19; S, 16.05.

EXAMPLE 2 In the same manner as described in Example 1, grams (0.124mol) of bis(trifiuoromethyl)disulfide were reacted with grams (0.258mol) of chlorotrifluoroethylene by irradiating the mixture over a 1%hour period during which the temperature of refluxing liquid rose fromC. to 84 C. when refluxing and irradiation were discontinued. Thecontents of the reflux flask were then distilled and yielded as a majorfraction, 22.9 grams (a 52% yield) of1,4-bis(trifluoromethylthio)-l,l,2,3,4,4-liexafluero-Z,3-dichlorobutane,

FCSCF CFCICFCICF SCF 177 C. The ide'ritity of thebis(trifluoromethylthio) hexafluorodichlorobutane was shbwn by F. N.M.R.ex-

amination to be symmetrical. No trace other possible isomers was found.Elemental analysis showed;

4 Calcd. (percent): C, 16.56; S, 14.74; Cl, 16.30. Found (percent): C,16.87; S, 14.75; Cl, 16.31.

EXAMPLE 3 In the same manner as described in Example 1, 202 grams ofbis(trifluoromethyl)disulfide were reacted with 64 grams ofdifluoroethylene (CF CH over a period of one hour and 50 minutes duringwhich the temperature of the refluxing liquid rose from 35 C. to 110 C.The liquid in the flask was then removed and distilled. At atmosphericpressure distillation was accompanied by decomposition. Distillation atC. under 75 mm. Hg yielded 11.2 grams of1,4-bis(trifluoromethylthio)-l,l,4,4- tetrafluorobutane, F CSCF CH CH CFSCF Elemental analysis showed:

Calcd, (percent): C, 16.56; S, 14.74; Cl, 16.30. Found (percent): C,22.13; H, 1.24; S, 19.25.

EXAMPLE 4 The 1,4-bis(trifluoromethylthio) perfluorobutane of Example land the 1,4-bis(trifluoromethylthio) hexafluorodichlorobutane of Example2 were tested for thermal sta bility by storing samples of the compoundsin sealed Pyrex glass tubes at 200 C. for 7 days. Both samples remainedunchanged during the entire course of the test evidencing completethermal stability under conditions of the test.

A sample of l,4-bis(trifluoromethylthio) tetrafluorobutane of Example 3was similarly tested and failed by turning black after 24 hours.

When tested at 250 C. the compound of Example 1 was stable for 7 days;when tested at 350 C. the compound of Example 1 decomposed completely tooctafluorothiolane.

over a period of 7 days. The resulting octafluorothiolane is stableduring, and at the end of a 7 day exposure to a temperature of 350 C.

The compound of Example 1 therefore is further useful as a startingmaterial for the production of octafluorothiolane which in turn isuseful as a'fire extinguishing liquid.

EXAMPLE 5 The 1,4 bis(trifluoromethylthio) 1,l,4,4 octafluorobutane ofExample 3 was tested as an insecticidal fumigant against confused flourbeetle (CFB), black carpet beetle (BCB), yellow meal worm (YMW) andnematodes (NEM) by placing l0 insects of each species (except thenematodes, of which about were used) in 1.5 inch diameter salve tinswith perforated lids. A small amount of appropriate food was placed ineach tin. The tins were placed in gallon jars and appropriate dosages ofabout 0.05 ml. of the toxicant per jar were placed on cellucotton wadsin small open containers and placed in the jars, thus providing vaporconcentrations of toxicant in the jar of about 1 lb. toxicant vapor per1000 square feet of air in the jars. After 24 hours exposure the insectcontainers were removed from the jars, and mortality counts madeimmedaitely and at 1 day intervals for 7 days. Mortality results after 7days are shown in Table I below.

TABLE I 7 day mortality in percent dead at dosage 1 lb.

per Cu. ft.

Percent kill Confused flour beetle (adults) 100 Black carpet beetle(larvae) u 100 Yellow meal worm (larvae) 60 Nematodesa===a===a==a====e:.;;;;;.;;m;u;5;=;; 1G9

5 We claim: 1. Bis(trifluoromethy1thio) fluorobutanes of the formulawherein X and Y are the same or different members selected from thegroup consisting of hydrogen, fluorine and chlorine with the provisosthat only one of X and Y is chlorine and that when X is hydrogen, Y isalso hydrogen.

2. 1,4-bis(trifiuoromethylthio) perfluorobutane of the formula 3. 1,4bis(trifluoromethylthio)-1,1,2,3,4,4-hexafluoro- 2,3-dichlorobutane ofthe formula 4. 1,4 bis(trifluoromethylthio)-1,1,4,4-tetrafluorobutane ofthe formula References Cited UNITED STATES PATENTS 2,730,543 5/1950Rendallet al 260-609A CHARLES B. PARKER, Primary Examiner D. R.PHILLIPS, Assistant Examiner

